the apple test (2025 Update)

Haven't we been through this before?

Or so they say. There's no way to know what goes on in someone else's head.

The important thing to remember is... there is no apple.

Apples are real.

But we can build the circuit, and it might work.

There are tests for visualization skill. The US Marine Corps wants people with good vizualization and dynamics, so they have one test that shows flat pieces of cardboard with printed patterns, and a bunch of boxes, one of which can be folded up from the cardboard. Fun. I aced that one but didn't want to be a Marine.

This was discussed on SED in September 2024 in the thread titled "Visualizing".

Programming per se is logic, not physics.

There has been lots of research on performing mental rotation of a figure or object, based on how long it takes to answer a question that requires mental rotation. Turns out that the delay is proportional to the magnitude (in degrees) of the required rotation, and not the direction, as I recall. It does not much depend on IQ.

This implies that there is a physical area in the brain that performs rotation, and how well this works will thus vary from person to person.

Well, maybe they're just arrogant and entitled. Manners don't arise from or require the mental ability to visualize a rotating apple.

Joe Gwinn

ISTR we have.

I just find it bizarre that some people can't. I have no difficulty seeing it in great detail 3D technicolour and the perspective manipulation is no problem, either. There again, I was equally astonished when I discovered that not everyone dreams in colour as that was also something I'd always taken for granted. BTW, being able to visualise 3D objects in space has not assisted me in the least with laying out a board in advance and the are invariably no shortage of items I fail to allow space/clearance/connectivity-convenience for. And my visio-spatial awareness *in practice* is equally hopeless. So there must be something more to it.

Except imaginary ones.

But some imaginary things might be real.

I said that I suspected half.

My wife is neither arrogant nor entitled. But she wouldn't be a good line chef; she can't navigate or anticipate other peoples' paths, in a kitchen or on the road. She's a superb speech pathologist.

Motion is yet another dimension of visualization.

They're real alright. You can't describe things like complex impedance or the plotting of a Smith Chart without recourse to them.

But do they exist?

Visualisaton is just one way of thinking about a problem. John Larkin thinks that he can do it well, and consequently thinks that it is a uniquely valuable skill.

He doesn't seem to have a clue about all the other ways of getting your head around a problem, and can't recognise any of them when other people try to talk about them.

I was amazed to realise that I dream left-right reversed.

I had one particularly vivid dream in which the layout of the house where it took place was evidently important. I woke and sketched a plan of the house on a scrap of paper. The next morning I tried to work out where the dream took place, but didn't know of anywhere that fitted the plan. Then I tried viewing it in mirror-image and it became immediately apparent where it was.

Since then, whenever I remember a dream, I check to see if it was mirror-image and there is almost always a clue somewhere that it was.

I think the fact that I am left-handed may be part of the explanation. I am sure it explains why I found it so easy to work on mirror-image printed circuit board layout drawings and then found it difficult to come back to working right-way-around.

Are you sure you weren't just imagining it?

Certainly complex impedances can be visualized and analyzed in time domain. Better than in classic slide-rule-days RF terms.

There certainly is a highly useful role for TD in this area. In fact by using a TDR and a VNA together one can disintangle multiple reflections on a network and uncover discontinuities that are obscured by other reflections. I really should get a TDR; it's about the only piece of test kit (apart from a curve tracer) I don't own. Must remedy those shortcomings as a priority!

TDR is a fabulous tool. You can see exactly where things are happening on a board or in a box, and fix it there. That's really hard to do in the frequency domain.

You can also investigate urban legends, like the terrible effects of right-angle bends in PCB traces.

I don't have a curve tracer and don't miss it. The occasional subtle semiconductor measurement can be done with bench instruments. A classic curve tracer won't report capacitance-vs-voltage, or pA leakages, or step-recovery, or any really interesting stuff.

Data sheets have curves.

It would be fun to have a small USB curve tracer that does measure capacitances and fA currents.

Carp, another youtube rabbit hole!

John ;-#(#

or it may be 'lateral'...

From our PoV, that's irrelevant. They're a very useful expedient without which our lives would be rather more problematic.

Complex impedances don't exist in the time domain, which is one-dimensional, and you can keep track of complex impedances with a slide rule - mine had sine and cosine transformations built in. Tan would have been tricky.

One has to wonder what John Larkin was taught at Tulane - he clearly hasn't retained much of it.